A pitman of a jaw crusher has an upper part, which includes an upper supporting point for supporting the pitman in the body of the jaw crusher, and a lower part having a lower supporting point for supporting the pitman in the body of the jaw crusher through a toggle plate. A second main face of the substrate is mechanically processed to form a slab, so that the recesses pass through the substrate to form through holes. The present invention is furthermore a process and a system for monitoring a drainage element.